Life in world's driest desert seen as sign of potential life on Mars

For the first time, researchers have seen life rebounding in the world's driest desert, demonstrating that it could also be lurking in the soils of Mars.

Hyperarid core of the Atacama Desert [Credit: Dirk Schulze-Makuch]

Led by Washington State University planetary scientist Dirk Schulze-Makuch, an international team studied the driest corner of South America's Atacama Desert, where decades pass without any rain.

Scientists have long wondered whether microbes in the soil of this hyperarid environment, the most similar place on Earth to the Martian surface, are permanent residents or merely dying vestiges of life, blown in by the weather.

In a new study published in the Proceedings of the National Academy of Sciences, Schulze-Makuch and his collaborators reveal that even the hyper-arid Atacama Desert can provide a habitable environment for microorganisms.

The researchers found that specialized bacteria are able to live in the soil, going dormant for decades, without water and then reactivating and reproducing when it rains.

"It has always fascinated me to go to the places where people don't think anything could possibly survive and discover that life has somehow found a way to make it work," Schulze-Makuch said. "Jurassic Park references aside, our research tell us that if life can persist in Earth's driest environment there is a good chance it could be hanging in there on Mars in a similar fashion."

The dry limit of life

When Schulze-Makuch and his collaborators went to the Atacama for the first time in 2015 to study how organisms survive in the soil of Earth's driest environment, the craziest of things happened. It rained.

After the extremely rare shower, the researchers detected an explosion of biological activity in the Atacama soil.

These are the surfaces of Mars and the Atacama Desert [Credit: NASA (left) / Alessandro Airo, TU Berlin (right)]

They used sterilized spoons and other delicate instrumentation to scoop soil samples from various depths and then performed genomic analyses to identify the different microbial communities that were reproducing in the samples. The researchers found several indigenous species of microbial life that had adapted to live in the harsh environment.

The researchers returned to the Atacama in 2016 and 2017 to follow up on their initial sampling and found that the same microbial communities in the soil were gradually reverting to a dormant state as the moisture went away.

"In the past researchers have found dying organisms near the surface and remnants of DNA but this is really the first time that anyone has been able to identify a persistent form of life living in the soil of the Atacama Desert," Schulze-Makuch said. "We believe these microbial communities can lay dormant for hundreds or even thousands of years in conditions very similar to what you would find on a planet like Mars and then come back to life when it rains."

Implications for life on Mars

While life in the driest regions of Earth is tough, the Martian surface is an even harsher environment.

It is akin to a drier and much colder version of the Atacama Desert. However it wasn't always this way.

Billions of years ago, Mars had small oceans and lakes where early lifeforms may have thrived. As the planet dried up and grew colder, these organisms could have evolved many of the adaptations lifeforms in the Atacama soil use to survive on Earth, Schulze-Makuch said.

"We know there is water frozen in the Martian soil and recent research strongly suggests nightly snowfalls and other increased moisture events near the surface," he said. "If life ever evolved on Mars, our research suggests it could have found a subsurface niche beneath today's severely hyper-arid surface."

Next Steps

On March 15, Schulze-Makuch is returning to the Atacama for two weeks to investigate how the Atacama's native inhabitants have adapted to survive. He said his research team also would like to look for lifeforms in the Don Juan Pond in Antarctica, a very shallow lake that is so salty it remains liquid even at temperatures as low as -58 degrees Fahrenheit.

"There are only a few places left on Earth to go looking for new lifeforms that survive in the kind of environments you would find on Mars," Schulze-Makuch said. "Our goal is to understand how they are able to do it so we will know what to look for on the Martian surface."

Author: Will Ferguson | Source: Washington State University [February 26, 2018]

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Model based on hydrothermal sources evaluate possibility of life on Jupiter's icy moon

Jupiter's icy moon Europa is a major target of astrobiology research in light of the possibility that it offers a habitable environment in the Solar System. Under its ice crust, estimated to be 10 km thick, is an ocean of liquid water of over 100 km deep. A huge source of energy deriving from gravitational interaction with Jupiter keeps this water warm.

Europa has an enormous ocean of warm liquid water under its frozen crust. The bottom of this ocean could
be a similar environment to primitive Earth, potentially hosting microorganisms [Credit: NASA]

Theoretical research to evaluate the microbial habitability of Europa using data collected from analogous environments on Earth has been conducted by a group of Brazilian researchers linked to the University of Sao Paulo (USP) that jointly authored an article published in Scientific Reports.

"We studied the possible effects of a biologically usable energy source on Europa based on information obtained from an analogous environment on Earth," said Douglas Galante, a researcher at Brazil's National Synchrotron Light Laboratory (LNLS) and the Astrobiology Research Center (NAP-Astrobio) of the University of Sao Paulo's Institute of Astronomy, Geophysics & Atmospheric Sciences (IAG-USP).

Galante coordinates the study, supported by the Sao Paulo Research Foundation -- FAPESP through a Master's fellowship from chemist Thiago Pereira, co-author of the article who has in Galante his supervisor, and through a Thematic Project which aims at investigating places in Brazil and Africa with possible vestiges of geochemical and isotopical transformations related to the emergence of multicelular life in Neoproterozoic Age.

Similarities with primitive earth

In the Mponeng gold mine near Johannesburg, South Africa, at a depth of 2.8 km, the research project not only found traces of major changes linked to history of life on Earth, but also a terrestrial context analogous to Europa. It was recently discovered that the bacterium Candidatus Desulforudis audaxviator survives inside the mine without sunlight by means of water radiolysis, the dissociation of water molecules by ionizing radiation.

"This very deep subterranean mine has water leaking through cracks that contain radioactive uranium," Galante said. "The uranium breaks down the water molecules to produce free radicals [H+, OH-, and others]. The free radicals attack the surrounding rocks, especially pyrite [iron disulfide, FeS2], producing sulfate. The bacteria use the sulfate to synthesize ATP [adenosine triphosphate], the nucleotide responsible for energy storage in cells. This is the first time an ecosystem has been found to survive directly on the basis of nuclear energy."

According to Galante and colleagues, the environment colonized by bacteria in the Mponeng mine is an excellent analogue of the environment assumed to exist at the bottom of Europa's ocean.

Although the temperature in Europa's surface is next to absolute zero, there is an enormous amount of thermal energy in its core, as an effect of Europa's interaction with Jupiter's powerful gravitational attraction, which causes the satellite's orbit to be extremely elliptical, meaning Europa finds itself either to close or too far from the Gas Giant. That makes the icy moon to suffer geometrical deformation as it moves at the mercy of Jupiter's immense tidal force. The energy released by the alternating states of elongation and relaxation makes Europa's subsurface capable of hosting an ocean of liquid water.

"However, it's not enough for there to be heated liquid water," said Galante. According to the researcher, the basis for all biological activity known to Earth are the chemical gradients, i.e., differences in concentrations of molecules, ions or electrons in distinct regions which produce a flow in a certain direction, allowing the occurrence of cellular respiration, photosynthesis, ATP production and other processes common to living beings.

"Hydrothermal emanations -- of molecular hydrogen [H2], hydrogen sulfide [H2S], sulfuric acid [H2SO4], methane [CH4] and so on -- are important sources of chemical imbalance and potential factors of 'biological transduction', i.e., transformation of the imbalance into biologically useful energy," Galante said. "These hydrothermal sources are the most plausible scenario for the origin of life on Earth."

Investigating conditions in Europa for ATP production

The group evaluated how chemical imbalance in Europa could be initiated through the emanation of water leading to chain reactions between water and chemical elements found in Europa's crust -- however, a total lack of empirical data prevents scientists from unequivocally presuming any of these events (an "Europa Mission" may take place as late as 2030, stated Nasa, the US space agency). "That's why we looked for a more universal physical effect that was highly likely to occur. That effect was precisely the action of radioactivity," Galante said.

Celestial bodies in the Solar System with rocky cores share the same radioactive materials, ejected in space by the Supernova explosion that originated the Sun and the planets. Uranium, thorium and potassium are the radioactive elements considered by the research, which estimated the concentrations for these materials in Europa, based on the quantities already observed and measured on Earth, in meteorites and in Mars.

"From these amounts, we were able to estimate the energy released, how this energy interacts with the surrounding water, and the efficiency of the water radiolysis resulting from this interaction in generating free radicals," Galante said.

According to the study, along with radionuclides, pyrite is a crucial ingredient whose presence is indispensable for life in Europa. "One of the proposals deriving from our study is that traces of pyrite should be looked for as part of any assessment of the habitability of a celestial body," stated Galante. Chances for finding pyrite in a hypothetical mission to Europa are good, since sulfur (S) and iron (Fe) are elements found in abundance across the Solar System.

"The ocean bed on Europa appears to offer very similar conditions to those that existed on primitive Earth during its first billion years. So studying Europa today is to some extent like looking back at our own planet in the past. In addition to the intrinsic interest of Europa's habitability and the existence of biological activity there, the study is also a gateway to understanding the origin and evolution of life in the Universe."

Author: Jose Tadeu Arantes | Source: Fundacao de Amparo a Pesquisa do Estado de Sao Paulo [February 23, 2018]

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Earth holds the key to detecting life beyond our solar system

New research in to how Earth's atmosphere evolved over time could hold the key to detecting life on exoplanets, according to scientists from the University of St Andrews and Cornell University.

Credit: NASA

The new study, published in The Astrophysical Journal, details how Earth's atmosphere evolved over time and how this corresponds to the appearance of different forms of life.

The team, led by Dr Sarah Rugheimer, astronomer and astrobiologist from the School of Earth and Environmental Sciences at the University, studied different geological epochs from Earth's history, modelling the atmospheres around different stars, bigger and smaller than our Sun. The researchers found that a planet's star type is an important factor in how an exoplanet's atmosphere develops and in how detectable signs of life, aka biosignatures, will be.

The study focussed on Earth’s atmosphere at four distinct points in history: before microbes (3.9 billion years ago), after microbes and the first rise of oxygen (2 billion years ago), during the second rise of oxygen (800 million years ago), and Earth as it is today. At each of these points, oxygen, methane and carbon dioxide were in drastically different abundances.

The new findings in to how life evolves in different atmospheres could lay the foundation for scientists to interpret early biosignatures and signs of life on Earth-size exoplanets.

Lead researcher Dr Rugheimer said: “We expect to find a myriad of exoplanets beyond even our wildest imagination. Even looking back at our own planet, the atmosphere has changed dramatically many times. By looking at the history of Earth and how different host star light would interact with a planet’s atmosphere, we can start to create a grid of models to help us understand future observations. In particular, in this paper we wanted to find out how detectable biosignature gases have been both in Earth's history and if these planets were orbiting a different star.”

Varied cloud cover and surface features such as oceans and continents were also factored in during the study to see how these affected the models, however in order to accurately reflect the findings on distant exoplanets larger telescopes are required.

Dr Rugheimer notes: “The 2019 launch of the James Webb Space Telescope should allow us to study a handful of habitable, Earth-size exoplanets transiting red dwarf stars. The European Extremely Large Telescope, which should be online in the mid-2020s, may also be able to directly image a handful of exoplanets.”

Source: University of St Andrews [February 19, 2018]

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Asteroid 'time capsules' may help explain how life started on Earth

In popular culture, asteroids play the role of apocalyptic threat, get blamed for wiping out the dinosaurs -- and offer an extraterrestrial source for mineral mining.

Credit: Pixabay

But for researcher Nicholas Hud, asteroids play an entirely different role: that of time capsules showing what molecules originally existed in our solar system. Having that information gives scientists the starting point they need to reconstruct the complex pathway that got life started on Earth.

Director of the NSF-NASA Center for Chemical Evolution at the Georgia Institute of Technology, Hud says finding molecules in asteroids provides the strongest evidence that such compounds were present on the Earth before life formed. Knowing what molecules were present helps establish the initial conditions that led to the formation of amino acids and related compounds that, in turn, came together to form peptides, small protein-like molecules that may have kicked off life on this planet.

"We can look to the asteroids to help us understand what chemistry is possible in the universe," said Hud. "It's important for us to study materials from asteroids and meteorites, the smaller versions of asteroids that fall to Earth, to test the validity of our models for how molecules in them could have helped give rise to life. We also need to catalog the molecules from asteroids and meteorites because there might be compounds there that we had not even considered important for starting life."

Hud will be a panelist at a press briefing "Asteroids for Research, Discovery, and Commerce" on February 17 at the 2018 annual meeting of the American Association for the Advancement of Science (AAAS) in Austin, Texas.

NASA scientists have been analyzing compounds found in asteroids and meteorites for decades, and their work provides a solid understanding for what might have been present when the Earth itself was formed, Hud says.

"If you model a prebiotic chemical reaction in the laboratory, scientists can argue about whether or not you had the right starting materials," said Hud. "Detection of a molecule in an asteroid or meteorite is about the only evidence everyone will accept for that molecule being prebiotic. It's something we can really lean on."

The Miller-Urey experiment, conducted in 1952 to simulate conditions believed to have existed on the early Earth, produced more than 20 different amino acids, organic compounds that are the building blocks for peptides. The experiment was kicked off by sparks inside a flask containing water, methane, ammonia and hydrogen, all materials believed to have existed in the atmosphere when the Earth was very young.

Nicolas Hud, director of the NSF-NASA Center for Chemical Evolution at the Georgia Institute of Technology
[Credit: Fitrah Hamid, Georgia Tech]

Since the Miller-Urey experiment, scientists have demonstrated the feasibility of other chemical pathways to amino acids and compounds necessary for life. In Hud's laboratory, for instance, researchers used cycles of alternating wet and dry conditions to create complex organic molecules over time. Under such conditions, amino acids and hydroxy acids, compounds that differ chemically by just a single atom, could have formed short peptides that led to the formation of larger and more complex molecules -- ultimately exhibiting properties that we now associate with biological molecules.

"We now have a really good way to synthesize peptides with amino acids and hydroxy acids working together that could have been common on the early Earth," he said. "Even today, hydroxy acids are found with amino acids in living organisms -- and in some meteorite samples that have been examined."

Hud believes there are many possible ways that the molecules of life could have formed. Life could have gotten started with molecules that are less sophisticated and less efficient than what we see today. Like life itself, these molecules could have evolved over time.

"What we find is that these compounds can form molecules that look a lot like modern peptides, except in the backbone that is holding the units together," said Hud. "The overall structure can be very similar and would be easier to make, though it doesn't have the ability to fold into as complex structures as modern proteins. There is a tradeoff between the simplicity of forming these molecules and how close these molecules are to those found in contemporary life."

Geologists believe the Earth was very different billions of years ago. Instead of continents, there were islands protruding from the oceans. Even the sun was different, producing less light but more cosmic rays -- which could have helped power the protein-forming chemical reactions.

"The islands could have been potential incubators for life, with molecules raining down from the atmosphere," Hud said. "We think the key process that would have allowed these molecules to go to the next stage is a wet-dry cycling like what we are doing in the lab. That would have been perfect for an island out in the ocean."

Rather than a single spark of life, the molecules could have evolved slowly over time in gradual progression that may have taken place at different rates in different locations, perhaps simultaneously. Different components of cells, for example, may have developed separately where conditions favored them before they ultimately came together.

"There is something very special about peptides, nucleic acids, polysaccharides and lipids and their ability to work together to do something they couldn't have done separately," he said. "And there could have been any number of chemical processes on the early Earth that never led to life."

Knowing what conditions were like on the early Earth therefore gives scientists a stronger foundation for hypothesizing what could have taken place, and could offer hints to other pathways that may not have been considered yet.

"There are probably a lot more clues in the asteroids about what molecules were really there," said Hud. "We may not even know what we should be looking for in these asteroids, but by looking at what molecules we find, we can ask different and more questions about how they could have helped get life started."

Source: Georgia Institute of Technology [February 17, 2018]

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Charged oxygen in ionosphere may offer biomarker for exoplanets

On January 9, 1992, astronomers announced a momentous discovery: two planets orbiting a pulsar 2,300 light years from our sun. The two planets, later named Poltergeist and Draugr, were the first confirmed “exoplanets”—worlds outside our solar system, circling a distant star. Scientists now know of 3,728 (confirmed) exoplanets in 2,794 systems, each one begging the question: “Is anyone else out there?”

The search for extraterrestrial life has focused mostly on exoplanets like Kepler-186f, shown here, which circle M-class stars
in a “habitable zone” where water may exist. But “not all habitable zones are created equal,” says Mendillo, who notes that
 some exoplanets are dangerously close to their stars, exposing them to hazardous radiation that might prevent life as we
know it. “Earth’s habitable zone has a little more hospitality” [Credit: NASA Ames/SETI Institute/JPL-Caltech]

“What more important question could we ask? Are we alone?” asks Boston University professor of astronomy Michael Mendillo. “I don’t know of any more fascinating question in science.”

For decades, astronomers have been searching these distant exoplanets for signs of life, mostly looking for that most essential molecule, water. But Mendillo and his colleagues have a different idea. In a paper published in Nature Astronomy, Mendillo, BU associate professor of astronomy Paul Withers, and PhD candidate Paul Dalba (GRS’18) suggest looking instead at an exoplanet’s ionosphere, the thin uppermost layer of atmosphere, which is whizzing with charged particles. Find one like Earth’s, they say, packed with single oxygen ions, and you have found life. Or, at least, life as we know it.

“Throughout the history of human civilization, we have never gotten to the point—until basically the last 15 years—where we could see planets around other stars. And now we’re at the point where we’re coming up with ideas to discover life outside Earth,” says John Clarke, professor of astronomy at Boston University, and director of the Center for Space Physics. “This is a great intellectual adventure that we’re on.”

Their work began when Mendillo and Withers received a grant from the National Science Foundation (NSF) to compare all planetary ionospheres in the solar system. (All the planets have them except Mercury, which is so close to the sun that its atmosphere is stripped off entirely.) Simultaneously, the team was also working with NASA’s MAVEN mission, trying to understand how the molecules that made up Mars’ ionosphere had escaped that planet. Since the early years of the Space Age, scientists have known that planetary ionospheres differ greatly, and the BU team started to focus on why that was the case, and why Earth’s was so different. While other planets stuff their ionospheres full of complicated charged molecules arising from carbon dioxide or hydrogen, Earth keeps it simple, with mostly oxygen filling the space. And it’s a specific type of oxygen—single atoms with a positive charge.

“I started thinking, how come our ionosphere is different than the other six?” recalls Mendillo.

The team ticked off numerous possibilities for Earth’s high concentration of O+ before settling on a culprit: green plants and algae.

“It’s because we have this atomic oxygen that traces its origin back to photosynthesis,” says Mendillo. “We have atomic oxygen ions, O+, in the ionosphere as a direct consequence of having life on the planet. So why don’t we see if we can come up with a criterion where the ionosphere could be a biomarker, not just of possible life but of actual life.”

A 10-minute, infrared exposure of Earth taken from the moon during the Apollo 16 mission.
The bright yellow is “dayglow” from atomic oxygen (O). On the dark side, “nightglow” bands,
arising from atomic oxygen ions (O+) in the ionosphere, can be seen near the equator
[Credit: NASA]

Most planets in our solar system have some oxygen in their lower atmospheres, but Earth has much more, about 21 percent. This is because so many organisms have been busy turning light, water, and carbon dioxide into sugar and oxygen—the process called photosynthesis—for the past 3.8 billion years.

“Destroy all the plants on Earth and our atmosphere’s oxygen will vanish away in mere thousands of years,” says Withers, who notes that all this oxygen exhaled by plants doesn’t just stick around the Earth’s surface. “To most people, O2, the oxygen we breathe, is not a very exciting molecule. To chemists, however, O2 is a wild, exhilarating, and perilous beast. It just will not sit still; it chemically reacts with almost any other molecule it can find and it does so very quickly.”

On Earth today, excess oxygen molecules, in the form of O2, float upward. When the O2 gets about 150 kilometers above the Earth’s surface, ultraviolet light splits it in two. The single oxygen atoms float higher, into the ionosphere, where more ultraviolet light and x-rays from the sun rip electrons from their outer shells, leaving charged oxygen zipping through the air. The abundance of O2 near the Earth’s surface—so different than the other planets—leads to an abundance of O+ high in the sky.

This finding, says Mendillo, suggests that scientists seeking extraterrestrial life could perhaps narrow their search area. Paul Dalba, who was working on exoplanet atmospheres with BU assistant professor of astronomy Philip Muirhead, joined the team to weigh in. “Dalba’s knowledge of star-exoplanet systems really helped,” Mendillo says. Currently, most scientists on this quest focus on M-class stars—the most abundant in the galaxy—and the planets circling them in the “habitable zone,” where water might exist.

This makes sense, because life as we know it needs water. But scientists don’t know exactly how much water a planet needs to support life. “If we only had the Mediterranean, would that have been enough? Do we need the Pacific, but not the Atlantic?” asks Mendillo. “If you look at the ionosphere, you don’t need to know the number. You just need to know that if the maximum electron density is associated with oxygen ions, then you’ve nailed it—you’ve got a planet where there’s photosynthesis and life.”

Of course, this assumes that “life” is at least somewhat analogous to life on Earth, which requires not only water and oxygen, but also a certain temperature range, probably a magnetic field, and other factors. “That’s a good starting point,” says Clarke. “But in the back of our mind, we are all aware that there may be kinds of life we’re not thinking about that may surprise us.”

There’s one other catch, at least for now: scientists don’t have the tools to detect an ionosphere on any exoplanet—yet. “If you look at the space telescopes that might come next, a lot is going to be possible,” says Clarke. “I think in ten years we will have the technology to do this experiment.”

Mendillo hopes his team’s work makes a case for further research, development, and exploration in this area. “Just the idea of using the ionosphere as a signature is a captivating idea,” he says. “We don’t have the observational capability yet, but I’m optimistic. We offer this up as a challenge.”

Author: Barbara Moran | Source: Boston University [February 16, 2018]

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Soft tissue fossil clues could help search for ancient life on Earth and other planets

Fossils that preserve entire organisms (including both hard and soft body parts) are critical to our understanding of evolution and ancient life on Earth. However, these exceptional deposits are extremely rare. The fossil record is heavily biased towards the preservation of harder parts of organisms, such as shells, teeth and bones, as soft parts such as internal organs, eyes, or even completely soft organisms, like worms, tend to decay before they can be fossilised. Little is known about the environmental conditions which stop this process soon enough for the organism to be fossilised.

The fossil Waptia from the Burgess Shale, Canada. New Oxford University research suggests that the mineralogy of the
surrounding earth is key to conserving soft parts of organisms, and finding more exceptional fossils like the Waptia
[Credit: Yale University]

New Oxford University research suggests that the mineralogy of the surrounding earth is key to conserving soft parts of organisms, and finding more exceptional fossils. Part-funded by NASA, the work could potentially support the Mars Rover Curiosity in its sample analysis, and speed up the search for traces of life on other planets.

Perhaps the most iconic of all exceptional fossil deposits is the Burgess Shale of Canada, popularised by Stephen J. Gould's Wonderful Life. Dating to around 500 million years ago, the deposit preserves exceptional fossils from the Cambrian Explosion, an event which saw the rapid diversification of early animal life from simpler single-celled ancestors. Burgess Shale-type fossil localities are now known across the globe and without them roughly 80% of Cambrian organisms (those that have no hard skeleton or shell) would be unknown, distorting our picture of early animal evolution.

Published in Geology, the study, conducted by researchers from Oxford's Department of Earth Sciences, Yale University, and Pomona College, builds on their previous research which revealed that certain clay minerals are toxic to bacteria that decay marine animals. This time around, the team set out to find geological evidence that rocks composed of the same clay minerals are the hosts of Burgess Shale-type fossils.

The team examined more than 200 Cambrian rock samples using powder X-ray diffraction analysis to determine their mineralogical composition, comparing rocks with Burgess Shale-type fossils with those with only fossilised shells and bones. Nicholas Tosca, Associate Professor of Sedimentary Geology at Oxford, said: 'The number of samples required for this study was made possible because the diffractometer at Oxford collects mineralogical data 250 times faster than a conventional instrument.'

The findings reveals that soft tissue fossils are generally found in rocks rich in the mineral berthierine, one of the main clay minerals identified by the previous study as being toxic to decay bacteria. Ross Anderson, lead author and fellow at All Souls College, Oxford, explains: 'Berthierine is an interesting mineral because it forms in tropical settings when the sediments contain elevated concentrations of iron. This means that Burgess Shale-type fossils are likely confined to rocks which were formed at tropical latitudes and which come from locations or time periods that have enhanced iron. This observation is exciting because it means for the first time we can more accurately interpret the geographic and temporal distribution of these iconic fossils, crucial if we want to understand their biology and ecology.'

The study provides a mineralogical signature which can be used to find the more elusive sites that are home to these extraordinary fossils. 'The mineralogical associations we identified mean that for a given Cambrian sedimentary mudrock we can predict with around 80% accuracy whether it is likely to contain Burgess Shale-type fossils,' explains Anderson.

Of the project's wider applications, potentially supporting the search for life beyond our own planet, Anderson adds: 'For the vast majority of Earth's history, life has not possessed hard shells or skeletons. This means that if we want to look for fossil evidence of life on other planets like Mars, the chances are we probably need to find fossils of entirely soft organisms, and Burgess Shale-type fossilisation provides a way. NASA's Curiosity rover has the ability to record mineralogy on the Martian surface, so it could potentially look for the types of rocks which might be most conducive to preserving these fossils.'

To expand their understanding of the exceptional preservation of soft organisms, the team are currently delving further back into Earth history, to investigate the preservation of microbes before macroscopic organisms with skeletons or shells evolved.

Source: University of Oxford [February 15, 2018]

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